Download Cell count with Hemocytometer Viability of the cells

Cell count with Hemocytometer
Viability of the cells
 Hemocytometer is a specially designed glass slide
with a 0.1 mm³ chamber and counting grid for
determining the number of cells per unit volume of
suspension .
Hemocytometers are thicker than those for
conventional microscopy .
It is used for microbiology , cell culture and many
applications that require use of suspensions of cells it
is necessary to determine cell concentration one can
often determine cell density of suspension
spectrophotometrically however that from of
determination dose not allow an assessment of cell
viability .
 Principle : it is used by putting the cover slip on the
device and filling the space with a liquid containing
the cells you want to count , The fluid is usually
drawn into the space by capillary action .
 The device used for determining the number of cells per unit volume of a
suspension is called a counting chamber. It is the widely used type of chamber,
since it was mainly designed for performing blood cell counts. Now it is used to
count other types of cells and other microscopic particles as well.
 The hemocytometer was invented by Louis-Charles
Malassez. This is a special type of microscope slide
consists of two chambers, which is divided into nine
(1.0mm x 1.0mm) large squares which is separated
from one another by triple lines. The area of each is
1mm². Cover glass is supported over the chambers at a
height of 0.1mm. Because of that the entire counting
grid lies under the volume of 0.9 mm² on one side. The
cell suspensions are introduced into the cover glass.
The hemocytometer is placed on the microscope stage
and counted the cell suspension.
Glass microscope slide consists of rectangular indentation that
creates an 'H' shaped chamber at the centre. This chamber is
engraved with laser-etched grid of perpendicular lines. Two counting
areas with ruled grids are separated by the horizontal groove of the
'H'. There is also a very flat, reusable cover slip. The glass cover slip is
held at 0.1 mm above the surface of the counting areas by ground
glass ridges on either side of the vertical grooves of the H shape. The
device is carefully crafted so that the area bounded by the depth
and lines of the chamber is also known. Because the height is
constant, the volume of fluid above each square of the grid is known
with precision.
The hemocytometer is used by putting the cover
slip on the device, and filling the space with a
liquid containing the cells you want to count.
There is a "V" or notch at either end which is the
place where the cell suspension is loaded into
the hemocytometer. The fluid is usually drawn
into the space by capillary action. A cover glass,
which is placed on the sample, does not simply
float on the liquid, but is held in place at a
specified height. In addition to the grid
arrangement of squares of different sizes, allows
for an easy counting of cells. It is possible to
identify the number of cells in a specified volume
by using this way.
The ruled area of the hemocytometer consists of
several, large, 1 x 1 mm (1mm² ) squares, which
are subdivided in three ways; 0.25 x 0.25 mm
(0.0625 mm²), 0.25 x 0.20 mm (0.05 mm²) and
0.20 x 0.20 mm (0.04 mm²). The central, 0.20 x
0.20 mm marked, 1 x 1 mm square is further
subdivided into 0.05 x 0.05 mm (0.0025 mm²)
squares. Hold the cover slip( 0.1 mm) at the
raised edges of hemocytometer, which gives each
square a defined volume.
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